This application claims priority from Korean Patent Application No. 2004-47621, filed on Jun. 24, 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to an integrated circuit device, and more particularly, to a bit refresh circuit for refreshing register bit values, an integrated circuit device having the bit refresh circuit, and a method of refreshing register bit values.
2. Description of Related Art
FIG. 1 is a block diagram showing a conventional integrated circuit device 100 having a register. The integrated circuit device 100 comprises a memory 110, a register 120, and a logic circuit 130. The register 120 stores data for controlling the logic circuit 130 or digital values for setting operations of the logic circuit 130. The logic circuit 130 receives bit values output from the register 120 and various control signals, performs given operations, and outputs operation results. The memory 110 outputs data used to set bit values of the register 120. The memory 110 may be a ROM such as an erasable programmable read only memory (EPROM) and an electrically erasable programmable read only memory (EEPROM) or a DRAM. The memory 110 may be provided inside or outside the integrated circuit device 100.
The integrated circuit device 100 includes, for example, a liquid crystal display (LCD) driver integrated circuit (IC) used for a mobile apparatus. In addition, the integrated circuit device 100 may include a DRAM and a digital signal processing (DSP) chip comprising the register 120 for setting bit values by using data output from the memory 110.
The logic circuit 130 of the integrated circuit device 100 may erroneously operate due to external noise. For example, an LCD driver IC of a mobile device such as a mobile phone may be affected with external noise resulting from electrostatic defect (ESD), power bouncing, or a flash of light. In turn, the external noise may change bit values used to set a common voltage for a register or bit values used for gamma correction. As a result, errors on the screen of an LCD may occur due to an erroneous operation of an internal logic circuit. To solve the problem, there is proposed an approach for providing an ESD protection diode in the LCD driver IC. In addition, there is proposed another approach for periodically refreshing the bit values set in the register. However, in a case where the bit values are directly periodically refreshed from an external host to the register, it is difficult to refresh the bit values bit-by-bit for plural ICs in which bit values of the register are not uniform. Moreover, in a case where data stored in the memory 110 is periodically refreshed and applied to the register 120, there is a problem of reducing the lifetime of the memory 110 since durability of the memory 110 is deteriorated.